(a) The atomic configuration of Si(100)/SiOx/SiO2 colored by the Mülliken charge as in the scale bar after the MD simulation of the dry oxidation process. The corresponding radial distribution functions of (b) crystalline Si layer (c) SiOx suboxide layer, and (d) amorphous SiO2 layer.
Optimized configuration of the modeled Si(100)/(Si2O)4/α-quartz system and the band gap profiles of Si(100)/(Si2O) x /α-quartz along z-axis. The white, red, and cyan balls denote the Si, O, and H atoms, respectively. We added O atoms sequentially to increase the number of the Si2O layers under the α-quartz (see the sequence of O adatoms in the Si2O region). CBM and VBM are determined by the energy values where the density of states (states/eV) decreases to less than 0.001. Note that increasing the number of Si2O layers elevates their CBM in energy.
Schematic diagram of the simulated device structure is plotted. The x-direction is the transport direction.
CB profiles for the conventional model and the 4-layer-suboxide model are plotted together for comparison. Notice the presence of both the 6 Å thick suboxide layer and the 5 Å thick transition region in the SiO2 side.
Gate leakage current for the conventional Si/SiO2 abrupt interface model with no suboxide layer and the model proposed here are plotted together. The curves for 1, 2, 3, 4 layers are the number of the suboxide Si2O layers. Under low gate bias, the leakage current is suppressed due to the suboxide layer. Under high gate bias, the current gets larger than the conventional case due to the tunneling electrons in the high energy region.
Potential profiles and current density spectrums are plotted side-by-side for (a) a low gate bias (VG = 0.01 V) and (b) a high gate bias (VG = 1.35 V). The dashed lines represent the substrate's Fermi level, EF = −1.05 V.
Gate leakage current density at a fixed low gate bias (VG = 0.01 V) as a function of SiO2 thickness for the conventional Si/SiO2 abrupt interface model and the 4-layer-suboxide model.
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